Liquid crystal display having wide viewing angle

ABSTRACT

A liquid crystal display includes a first substrate with pixel electrodes, and a second substrate with a common electrode facing the first substrate. The common electrode has depression patterns corresponding to the pixel electrodes. The side wall of each depression pattern is at an angle of 30-120° with respect to the first substrate. The depression patterns of the common electrode are formed through making depression patterns at color filters. In this structure, the liquid crystal display bears wide viewing angle and good picture quality.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of Applicants' U.S. patentapplication Ser. No. 09/727,782 filed on Dec. 4, 2000, now U.S. Pat. No.6,593,982 which is a continuation in part of U.S. patent applicationSer. No. 09/431,157 filed on Nov. 1, 1999 now U.S. Pat. No. 6,717,637.

This application is files as a continuation in part of the pending U.S.patent application of Ser. No. 09/431,157 filed Nov. 1, 1999, assignedto the same asignee.

BACKGROUND OF THE INVENTION

(a) Field of the Invention

The present invention relates to a liquid crystal display and, moreparticularly, to a liquid crystal display which has a wide viewingangle.

(b) Description of the Related Art

Generally, liquid crystal displays have a structure where a liquidcrystal is sandwiched between two substrates, and the electric fieldapplied to the liquid crystal changes its arrangement to control lighttransmission.

Among them, the vertically aligned twisted nematic (VATN) liquid crystaldisplays have a pair of internal transparent substrates with transparentelectrodes, a liquid crystal sandwiched between the substrates, and twopolarizing plates externally attached to the substrates one by one. Theliquid crystal molecules are initially aligned perpendicular to thesubstrates and, under the application of an electric field, they arespirally twisted with a predetermined pitch while being oriented to beparallel to the substrates.

When the polarizing plates are normal to each other in the polarizingdirection, light is completely blocked when there is no application ofan electric field. That is, in the so-called normally black mode,brightness is very low at an off state and hence the contrast ratio ishigh compared to the usual TN liquid crystal display. However, under theapplication of voltage (particularly gray scale voltage), a significantdifference is present in retardation of light depending upon the viewingdirections as in the usual TN liquid crystal display, so that theviewing angle becomes too narrow.

In order to solve such a problem, it has been proposed that theelectrodes be patterned to generate fringe fields, and that the fringefields generate several micro-regions with different orientationdirections of the liquid crystal molecules. For instance, U.S. Pat. No.5,309,264 issued to Lien discloses a technique of forming X-shapedopening portions at the common electrode. U.S. Pat. No. 5,434,690 issuedto Histake et al. discloses a technique of forming opening portions atthe electrodes of the top and bottom substrates in an alternate manner.

However, the above techniques require a separate mask to pattern thecommon electrode. Furthermore, since the color filter pigments mayinfluence the liquid crystal, a protective layer must be formed on thecolor filters. It also generates serious textures at the periphery ofthe patterned electrodes.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a liquid crystaldisplay which has a wide viewing angle with improved picture quality.

This and other objects may be achieved by a liquid crystal displayhaving a color filter substrate and a thin film transistor arraysubstrate.

The color filter substrate is overlaid with color filters withdepression patterns, and a black matrix surrounding the color filters. Acommon electrode is formed on the color filters with the depressionpatterns to make partitioned orientations of the liquid crystalmolecules.

The black matrix may be overlapped with the depression patterns of thecolor filters to reduce the light leakage.

The thin film transistor array substrate faces the color filtersubstrate with pixel electrodes. The pixel electrodes are provided withopening patterns. When the opening patterns of the pixel electrodes, andthe depression patterns of the color filters proceed parallel to each inan alternate manner, stable orientations of the liquid crystal moleculesand a wide viewing angle can be obtained.

When the common electrode is formed by depositing thin indium tin oxideonto the substrate twice, the common electrode at the periphery of thedepression patterns can be prevented from being cut.

Furthermore, the common electrode also has depression patternscorresponding to those of the color filters, with the angle of the sidewall of the depression pattern of the common electrode being 30-120°with respect to the thin film transistor array substrate.

Storage capacitor electrodes are further formed at the thin filmtransistor array substrate. When viewed from the top side, the pixelelectrodes completely cover the storage capacitor electrodes at apredetermined region.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the invention, and many of the attendantadvantages thereof, will be readily apparent as the same becomes betterunderstood by reference to the following detailed description whenconsidered in conjunction with the accompanying drawings in which likereference symbols indicate the same or similar components, wherein:

FIGS. 1A and 1B are schematic views illustrating the basic structure ofa vertically aligned twisted nematic liquid crystal display according tothe present invention in black and white modes;

FIG. 2 is a plan view of a color filter substrate for a liquid crystaldisplay according to a first preferred embodiment of the presentinvention;

FIG. 3 is a cross sectional view of a color filter substrate taken alongthe III-III′ line of FIG. 2;

FIG. 4 is a cross sectional view of a liquid crystal display with thecolor filter substrate shown in FIG. 2;

FIG. 5 is a plan view of a liquid crystal display according to a secondpreferred embodiment of the present invention;

FIG. 6 is a cross sectional view of the liquid crystal display takenalong the VI-VI′ line of FIG. 5;

FIG. 7 is a plan view of a liquid crystal display according to a thirdpreferred embodiment of the present invention;

FIG. 8 is a cross sectional view of a liquid crystal display accordingto a fourth preferred embodiment of the present invention;

FIGS. 9A and 9B are amplified views of the liquid crystal display shownin FIG. 8 illustrating equipotential lines and light transmission curveswhen a side wall of a depression pattern is at an angle of 90° or 45°with respect to a substrate;

FIG. 10 is a plan view of a liquid crystal display according to a fifthpreferred embodiment of the present invention;

FIG. 11 is a cross sectional view of the liquid crystal display takenalong the XI-XI′ line of FIG. 10;

FIG. 12 is a cross sectional view of a liquid crystal display forcomparison with the liquid crystal display shown in FIG. 11;

FIG. 13 is a plan view of a liquid crystal display according to a sixthpreferred embodiment of the present invention; and

FIG. 14 is a plan view of a liquid crystal display according to aseventh preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Preferred embodiments of this invention will be explained with referenceto the accompanying drawings.

FIGS. 1A and 1B schematically illustrate the basic structure of avertically aligned twisted nematic liquid crystal display according tothe present invention when voltage is not applied to liquid crystalmolecules and when voltage is applied thereto, respectively.

As shown in the drawings, the liquid crystal display includes two glassor quartz-based substrates 10 and 20 facing each other. Electrodes 11and 21 based on a transparent conductive material such as indium tinoxide (ITO), and vertical alignment layers 12 and 22 are internallyformed on the substrates 10 and 20 in a sequential manner. A liquidcrystal layer 100 based on a liquid crystal material having a negativedielectric anisotropy is interposed between the alignment layers 12 and22. The liquid crystal layer 100 may have chirality, or the alignmentlayers 12 and 22 may keep the layer 100 twisted. Polarizing plates 13and 23 are externally attached to the substrates 10 and 20 to polarizethe light passing through the liquid crystal layer 100 as well as thelight incident upon the liquid crystal layer 100. The polarizing axes ofthe polarizing plates 13 and 23 are at an angle of 90° to each other.

As shown in FIG. 1A, the long axial directions (the so-called directors)of the liquid crystal molecules 110 are initially aligned to beperpendicular to the substrates 10 and 20 due to the alignment layers 12and 22. In this state, the light linearly polarized through thepolarizing plate 23 attached to the bottom substrate 20 passes throughthe liquid crystal layer 100 in a direct manner. Then, the light isintercepted by the polarizing plate 13 attached to the top substrate 10so that the liquid crystal display comes to be in a black state.

When a potential difference is made at the electrodes 11 and 21 underthe application of voltage, an electric field is formed such that thedirection thereof is perpendicular to the substrate 10 and 20.Accordingly, the orientation directions of the liquid crystal molecules110 are changed under the influence of the electric field.

As shown in FIG. 1B, when the electric field reaches a predetermineddegree due to the large potential difference between the electrodes 11and 21, the directors of the liquid crystal molecules 110 are orientedto be perpendicular to the direction of the electric field or parallelto the substrates 10 and 20 due to the dielectric anisotropy. But theliquid crystal molecules 110 positioned close to the alignment layers 12and 22 are kept in the initial state because the alignment force of thealignment layers 12 and 22 exceeds the force of their dielectricanisotropy. Meanwhile, the liquid crystal molecules 110 are spirallytwisted due to chirality. When the chirality is controlled in anappropriate manner, the directors of the liquid crystal molecules 110can be rotated by 90° through the range from the bottom alignment layer22 to the top alignment layer 12.

The light polarized through the polarizing plate 23 attached to thebottom substrate 20 passes through the liquid crystal layer 100 whilebeing rotated by 90° at the polarizing axis thereof along the twisteddirections of the directors, and passes by the polarizing plate 13attached to the top substrate 10. Therefore, the liquid crystal displaycomes to be in a white state.

FIG. 2 is a plan view of a color filter substrate for a liquid crystaldisplay according to a first preferred embodiment of the presentinvention, and FIG. 3 is a cross sectional view of the color filtersubstrate taken along the III-III′ line of FIG. 2.

As shown in the drawings, the color filter substrate 10 is overlaid witha black matrix 14 that defines pixel areas. The black matrix 14 isformed of metal such as chrome, or organic black resist. Color filters15 of red, green and blue are formed at the pixel areas defined by theblack matrix 14. Each color filter 15 has a longitudinal depressedportion 150 centrally proceeding in the vertical direction. A commonelectrode 11 is formed on the black matrix 14 and the color filters 15of a transparent conductive material such as ITO.

In the fabrication process, a black matrix is first formed on asubstrate through depositing metal such as chrome or black resistthereon, and patterning it.

Thereafter, a resist of red, green or blue is deposited onto thesubstrate, and patterned to form color filters with depressed portions.

Finally, a transparent conductive material such as ITO is deposited ontothe black matrix and the color filters to form a common electrode. Sincethe common electrode is easily cut and disconnected due to the steppedarea on the depressed portion of the color filters, it is preferable toform the common electrode by depositing the conductive material twice,each time with a slight thickness.

The liquid crystal molecules 110 are initially kept perpendicular to thesubstrates 10 and 20 so that the liquid crystal display is in a blackstate as with the non-patterned color filters.

When voltage is applied, as shown in FIG. 4, electric fields in mostplaces are perpendicular to the substrates 10 and 20, but the electricfield close to the depressed portion 150 of the color filter 15 hascurved equipotential lines.

As the liquid crystal has a negative dielectric anisotropy, theorientation directions of the liquid crystal molecules 110 tend to beperpendicular to the direction of the electric field. Therefore, thedirectors of the liquid crystal molecules close to the depressed portion150 of the color filter 15 are twisted while being inclined with respectto the substrates 10 and 20. In this way, two micro-regions where theinclined directions of the liquid crystal molecules 110 are opposite toeach other around the center line of the depressed portion 150 of thecolor filter 15 are present, and optical characteristics at the tworegions compensate for each other, resulting in a wide viewing angle.

The technique of forming depressed portions at the color filters 15 torealize partitioned orientation of the liquid crystal molecules 110 maybe easily performed compared to other techniques such as rubbing, andcan control the micro-regions very much in detail while varying theshape of the depressed portions.

The depressed portion of the color filter 15 may have a depth identicalwith the thickness of the color filter 15, or smaller than the thicknessof the color filter 15.

FIG. 5 is a plan view of a liquid crystal display according to a secondpreferred embodiment of the present invention where one pixel area isillustrated, and FIG. 6 is a cross sectional view of the liquid crystaldisplay taken along the VI-VI′ line of FIG. 5. In this preferredembodiment, the depressed patterns of the color filters 15 areexemplified as the opening patterns where the color filters 15 arecompletely removed. Of course, it is possible that the color filters 15are only partially removed to form the depressed patterns.

As shown in the drawings, a plurality of linear opening portions arepresent at one pixel area 300. That is, first and second linear openingportions 211 and 212 are formed at the color filter 15 of the topsubstrate 10 while proceeding in the vertical and horizontal directions,and third and fourth linear opening portions 216 and 217 are formed atthe electrode 21 of the bottom substrate 20 while proceeding in thevertical and horizontal directions.

The first and second opening portions 211 and 212 formed at the topsubstrate 10 are separated from each other, and arranged in the verticaldirection while roughly forming four squares.

The third opening portion 216 formed at the bottom substrate 20centrally proceeds at the pixel area 300 in the vertical direction whilevertically bisecting the four squares formed by the first and secondopening portions 211 and 212. Both ends of the third opening portion 216nearly reach the second opening portions 212. In contrast, the fourthopening portions 217 proceed at the pixel area 300 in the horizontaldirection while horizontally bisecting the corresponding square formedby the first and second opening portions 211. Both ends of the fourthopening portions 217 nearly reach the first opening portions 211.

Therefore, the opening portions 211, 212, 216 and 217 at the twosubstrates 10 and 20 together form square-shaped micro-regions where thefirst and second opening portions 211 and 212 form the neighboringsides, and the third and fourth opening portions 216 and 217 form theremaining neighboring sides.

In the above structure, as shown in FIG. 6, the liquid crystal molecules110 are inclined due to the fringe fields close to the opening portions.The fringe fields close to the first and third opening portions 211 and216 direct the liquid crystal molecules toward the first openingportions 211 from the third opening portion 216. Therefore, theorientation directions of the liquid crystal molecules aredifferentiated while taking the opening portions 211 and 216 as theboundary.

Since the neighboring opening portions defining the square-shapedmicro-region are perpendicular to each other, the directors of theliquid crystal molecules within the micro-region vary in position. Asindicated by arrows in FIG. 5, the directors of the liquid crystalmolecules are directed in four average directions while proceedingtoward the angular points of the square-shaped micro-regions from thecenter thereof.

In this way, sixteen square-shaped micro-regions are formed at one pixelarea, and the directors of the liquid crystal molecules within eachmicro-region are directed in one of the four average directions. Thedirectors of the liquid crystal molecules in the neighboringmicro-regions are at an angle of 90

to each other when viewed from the top side.

Furthermore, when the polarizing axes P1 and P2 of the polarizing platesare established to be perpendicular to each other in the horizontal andvertical directions, the directors of the liquid crystal moleculeswithin each micro-region are at an angle of 45° with respect to thepolarizing axes P1 and P2 of the polarizing plates when voltage isapplied.

FIG. 7 is a plan view of a liquid crystal display according to a thirdpreferred embodiment of the present invention.

As shown in FIG. 7, a plurality of X-shaped opening portions 400 areformed at each pixel electrode of the bottom substrate while proceedingin the vertical direction, and linear opening portions 500 are formed atthe corresponding color filter while each crosses the center of theX-shaped opening portions 400.

Of course, the shape of depression patterns including opening patternsformed at the top and bottom substrates may change in various manners.

FIG. 8 is a cross sectional view of a liquid crystal display accordingto a fourth preferred embodiment of the present invention.

As shown in FIG. 8, the liquid crystal display includes a bottomsubstrate 1, a top substrate 60, and a liquid crystal 90 sandwichedbetween the bottom and top substrates 1 and 60. The bottom and topsubstrates 1 and 60 are formed with a transparent insulating materialsuch as glass.

Pixel electrodes 50 are formed on the bottom substrate 1 with atransparent conductive material such as indium tin oxide (ITO) andindium zinc oxide (IZO) with each having an opening pattern 51. Thepixel electrode 50 is connected to a switching circuit 2 to receivepicture image signal voltage. A thin film transistor (TFT) is used asthe switching circuit 2. The TFT is connected to a gate line (not shown)for transmitting scanning signals thereto and a data line (not shown)for transmitting picture image signals thereto. The pixel electrode 50turns on or off according to the scanning signal. A bottom polarizingplate 3 is externally attached to the bottom substrate 1. In the case ofreflection type liquid crystal displays, the pixel electrode 50 may beformed with a non-transparent material, and the bottom polarizing plate3 may not be necessary.

The top substrate 60 facing the bottom substrate 1 is sequentiallyoverlaid with a black matrix 70 surrounding color filters 61, and acommon electrode 80. The common electrode 80 is formed with atransparent conductive material such as ITO or IZO.

Each color filter 61 is provided with a depression pattern, and thecommon electrode 80 formed on the color filters 61 has depressionpatterns 81 corresponding to those of the color filters 61.

The black matrix 70 surrounding the color filters 61 is also formedunder the depression patterns 81 of the common electrode 80 to preventlight leakage caused by the depression patterns 81.

The black matrix 70 is usually formed with a conductive material such aschrome, but may be formed with an organic material. When the blackmatrix 70 is formed with a conductive material, it also functions as aconduction passage for passing a signal for the common electrode 80,thereby reducing resistance of the common electrode 80.

The above structure can have wide viewing angle characteristics for thefollowing reasons.

When voltage is not applied to the display device, the liquid crystalmolecules 90 are kept aligned perpendicular to the substrates 1 and 60while being in a black state, as with the non-patterned commonelectrode.

When voltage is applied, as shown in FIG. 8, an electric field is formednormal to the substrates 1 and 60 in most places, but formed in a curvedshape along the depression pattern of the common electrode 80.Therefore, the equipotential lines between the substrates 1 and 60 arenot parallel thereto, but curved in accordance with the shape of thecommon electrode 80. Consequently, the electric field does not alsoproceed normal to the substrates 1 and 60, but is slightly inclined.

As the liquid crystal has a negative dielectric anisotropy, theorientation directions of the liquid crystal molecules tend to be normalto the direction of the electric field. Therefore, the long axes of theliquid crystal molecules close to the depression pattern 81 are twistedand inclined with respect to the substrates 1 and 60. In this way, tworegions where the inclined directions of the liquid crystal moleculesare opposite to each other are divided around the center line of thedepression pattern 81 so that the optical characteristics at the tworegions compensate for each other, resulting in a wide viewing angle.

The relation between the shape of the depression pattern and the picturequality will be now described.

FIGS. 9A and 9B illustrate equipotential lines and light transmissioncurves where the side wall of the depression pattern is at an angle of90° or 45° with respect to the substrate.

When the angle between the side wall of the depression pattern and thesubstrate is 90°, as shown in FIG. 9A, the equipotential lines arecurved a lot at the bottom of the depression pattern of the commonelectrode 80 and at the top of the opening pattern of the pixelelectrode 50. Since the light transmission varies radically only at thedepression pattern and the opening pattern, textures are not shown ifthe depression pattern is covered. However, when the angle between theside wall of the depression pattern and the opening pattern is 45°, asshown in FIG. 2B, the equipotential lines become radically curved notonly at the bottom of the depression pattern of the common electrode 80and at the top of the opening pattern of the pixel electrode 50, butalso at the peripheral area of the depression pattern. The lighttransmission also varies radically at the depression pattern and theopening pattern as well as at the peripheral area of the depressionpattern. Therefore, textures are generated at the peripheral area of thedepression pattern.

As shown above, the smaller angle between the side wall of thedepression pattern and the substrate generates more widely spreadtextures around the peripheral area of the depression pattern.Therefore, it is preferable that the angle between the side wall of thedepression pattern and the substrate becomes great when measured fromthe side of the color filters 61. That angle is preferably 90° or more.However, when such an angle is 120° or more, the ITO-based commonelectrode is easy to be cut and disconnected at the depression pattern.

When the angle between the side wall of the depression pattern and thesubstrate is 45°, as shown in FIG. 9B, textures are generated at theperipheral area of the depression pattern. Nevertheless, they do notdeteriorate the picture quality in a serious manner. Furthermore, thedegree of textures can be controlled through varying the width of thedepression pattern or the width of the opening pattern of the pixelelectrode. Therefore, the lowest angle between the side wall of thedepression pattern and the substrate is about 30°.

FIG. 10 is a plan view of a liquid crystal display according to a fifthpreferred embodiment of the present invention, FIG. 11 is a crosssectional view of the liquid crystal display taken along the XI-XI′ lineof FIG. 10, and FIG. 12 is a cross sectional view of a liquid crystaldisplay for comparing with the liquid crystal display shown in FIG. 11.

Gate lines 4 are formed on a bottom insulating substrate 1 with gateelectrodes 5 while proceeding in the horizontal direction. Commonelectrode lines 6 and 7 are formed on the bottom substrate 1 whileproceeding parallel to the gate lines 4. The common electrode lines 6and 7 are connected to each other via two storage capacitor electrodes 8and 9 proceeding in the vertical direction. The number of commonelectrode lines 6 and 7 may be one, three or more. The gate lines 4, thegate electrodes 5, the common electrode lines 6 and 7, and the storagecapacitor electrodes 8 and 9 may be formed with a metallic material suchas aluminum or chrome while having a single-layered structure, or adouble-layered structure formed sequentially with a chrome-based layerand an aluminum-based layer.

A silicon nitride-based gate insulating layer 31 is formed on the gatelines 4, the common electrode lines 6 and 7, and the storage capacitorelectrodes 8 and 9.

Data lines 40 are formed on the gate insulating layer 31 in the verticaldirection. Source electrodes 41 are branched from the data lines 40, anddrain electrodes 42 are positioned close to the source electrodes 41while being separated from them. The data lines 40, the sourceelectrodes 41, and the drain electrodes 42 are formed with a metallicmaterial such as chrome or aluminum, in a single or multiple-layeredstructure.

A semiconductor layer (not shown) for forming TFT channels, and an ohmiccontact layer (not shown) for reducing contact resistance between thesemiconductor layer and the source and drain electrodes 41 and 42 areformed under the source and drain electrodes 41 and 42. Thesemiconductor layer is usually formed with amorphous silicon, and theohmic contact layer is formed with amorphous silicon doped with n-typeimpurities of high concentration.

A protective layer 32 is formed on the data lines 40 of an inorganicinsulating material such as silicon nitride or an organic insulatingmaterial such as resin. The protective layer 32 is provided with contactholes (not shown) opening the drain electrodes 42.

Pixel electrodes 50 are formed on the protective layer 32 with openingpatterns 51. The pixel electrodes 50 are formed with a transparentconductive material such as indium tin oxide (ITO) or indium zinc oxide(IZO), or an opaque conductive material such as aluminum that exhibits agood light reflection property.

The opening pattern 51 of each pixel electrode 50 has a horizontalopening portion formed at the boundary of the pixel electrode 50bisecting it into upper and lower regions, and inclined opening portionsformed at the upper and lower regions of the pixel electrode 50 whileproceeding perpendicular to each other, thereby uniformly distributingfringe fields in all directions.

The storage capacitor electrodes 8 and 9 are completely covered by thepixel electrode 50 at the A, B, C and D regions when viewed from the topside.

A black matrix 70 is formed at the top insulating substrate 60 toprevent leakage of light. Color filters 61 are formed on the topsubstrate 60 with depression patterns. A common electrode 80 is formedon the color filters 61 with depression patterns 81 corresponding tothose of the color filters 61. The depression patterns 81 of the commonelectrode 80 are formed due to the corresponding depression patterns ofthe color filters 61. The common electrode 80 is formed with atransparent conductive material such as ITO or IZO.

The depression pattern 81 of the common electrode 80 at a pixel area hasinclined depressed portions that externally proceed parallel to theupper and lower inclined opening portions of the pixel electrode 50, andlinear depressed portions bent from the inclined depressed portionswhile being overlapped with the sides of the pixel electrode 50. Thelinear depressed portions are classified into horizontal and verticallinear depressed portions. The sides of the pixel electrode 50overlapping the vertical linear depressed portions completely cover theunderlying storage capacitor electrodes 8 and 9.

In the above-structured liquid crystal display, textures can beeffectively prevented in the following respects.

FIG. 12 illustrates a liquid crystal display bearing occurrence oftextures. As shown in FIG. 12, when voltage is applied to a commonelectrode 800 and a pixel electrode 900, a strong electric field isformed between storage capacitor electrodes 230 and 240 and theperiphery of the pixel electrode 900. The strong electric fieldinfluences the electric field formed at the periphery of the pixel area.Particularly, such an influence becomes prominent at the A, B, C and Dregions where the common electrode 800 is provided with depressionpatterns 81. For that reason, the fringe field formed at the peripheryof the pixel area is inclined in a direction opposite to the directionof the fringe field formed at the center of the pixel area. Therefore,the orientation directions of the liquid crystal molecules arereverse-turned at the region T between the periphery and the center ofthe pixel area. Such a region T is displayed on the screen as a texture.

By contrast, in the liquid crystal display shown in FIG. 11, the pixelelectrode 50 completely covers the storage capacitor electrodes 8 and 9.Therefore, most of the electric lines of force formed between the pixelelectrode 50 and the storage capacitor electrodes 8 and 9 are connectedto the bottom surface of the pixel electrode 50. Consequently, theelectric field between the pixel electrode 50 and the storage capacitorelectrodes 8 and 9 does not influence the liquid crystal molecules. Thefringe fields that are not influenced by the storage capacitorelectrodes 8 and 9 are kept in the predetermined direction within thepixel area, and varied in direction out of the pixel area (while beingcovered by the black matrix). As the region T where the orientationdirections of the liquid crystal molecules are reverse-turned comes intobeing out of the pixel area while being covered by the black matrix,textures are not displayed at the screen.

FIG. 13 is a plan view of a liquid crystal display according to a sixthpreferred embodiment of the present invention. In this preferredembodiment, other components and structures of the liquid crystaldisplay are the same as those related to the fifth preferred embodimentexcept that the opening patterns 51 of the pixel electrodes 50, thedepression patterns 81 of the common electrode 80, the storage capacitorelectrodes 9, and the common electrode lines 6 have a differentstructure.

The opening pattern 51 of each pixel electrode 50 is formed withhorizontal opening portions and vertical opening portions. Thedepression pattern 81 of the common electrode 80 corresponding to theopening pattern 51 of the pixel electrode is formed with a peripheraldepressed portion overlapped with the periphery of the pixel electrode50, and a horizontal depressed portion placed between the horizontalopening portions of the pixel electrode 50.

The opening pattern 51 and the depression pattern 81 are overlapped witheach other to thereby divide the pixel area into several micro-regions.Each micro-region is shaped as a polygon having two longer sides thatare parallel to each other. Such a structure makes the response speed ofthe liquid crystal molecules fast. That is, the fringe field formed bythe opening pattern 51 and the depression pattern 81 makes the liquidcrystal molecules to be oriented parallel to each other. In this way,the liquid crystal molecules moves in one step and reduces the responsetime.

In the previous fifth preferred embodiment, the micro-regions divided bythe opening pattern and the depression pattern are also shaped as apolygon where the two longest sides thereof are parallel to each other.

The common electrode line 6 proceeds in the horizontal direction by oneper each pixel area, but may be formed in plurality. The commonelectrode line 6 is overlapped with the horizontal depressed portion ofthe depression pattern 81. The storage capacitor electrode 9 proceedsparallel to the left and right sides of the pixel electrode 50 whilebeing covered by the pixel electrode 50. This structure is to preventtextures.

FIG. 14 is a plan view of a liquid crystal display according to aseventh preferred embodiment of the present invention. In this preferredembodiment, other components and structures of the liquid crystaldisplay are the same as those related to the fifth preferred embodimentexcept that the opening patterns 51 of the pixel electrodes 50, thedepression patterns 81 of the common electrode 80, the storage capacitorelectrodes 9, and the common electrode lines 6 have a differentstructure.

The opening pattern 51 of each pixel electrode 50 is formed with aplurality of X-shaped opening portions. The depression pattern 81 isformed with a peripheral depressed portion and horizontal depressedportions while isolating the X-shaped opening portions from each other.

The common electrode line 6 proceeds in the horizontal direction withone for each pixel area, but it may be formed in a plural manner. Thecommon electrode line 6 is overlapped with one of the horizontaldepressed portions of the depression pattern 81. The storage capacitorelectrodes 9 proceed parallel to the left and right sides of the pixelelectrode 50 while being covered by the pixel electrode 50.

As described above, the inventive liquid crystal display involves a wideviewing angle, rapid response speed, and excellent picture quality.

While the present invention has been described in detail with referenceto the preferred embodiments, those skilled in the art will appreciatethat various modifications and substitutions can be made thereto withoutdeparting from the spirit and scope of the present invention as setforth in the appended claims.

1. A liquid crystal display, comprising: a first substrate; a pixelelectrode fanned on the first substrate; a storage capacitor electrodeformed on the first substrate; a second substrate facing the firstsubstrate; and a common electrode formed on the second substrate, thecommon electrode having a depression pattern; wherein the pixelelectrode completely covers the storage capacitor electrode at apredetermined region.
 2. The liquid crystal display of claim 1, whereinthe depression pattern overlaps the predetermined region at a sideportion of the pixel electrode.
 3. A liquid crystal display, comprising:a first substrate: a color filter formed on the first substrate andhaving a depressed portion, and a common electrode formed on the colorfilter; a second substrate facing the first substrate; a storagecapacitor electrode formed on the second substrate; a pixel electrodeformed on the second substrate and having an opening portion; and apixel region formed between the common electrode and the pixelelectrode, wherein the depressed portion is formed within the pixelregion and the pixel electrode completely covers the storage capacitorelectrode at a predetermined region.
 4. The liquid crystal display ofclaim 3, wherein the depressed portion has a depth smaller than the athickness of the color filter.
 5. The liquid crystal display of claim 4,further comprising a black matrix formed on the first substrate.
 6. Theliquid crystal display of claim 5, wherein the black matrix has aportion overlapped with the depressed portion.
 7. The liquid crystaldisplay of claim 6, wherein the depressed portion and the openingportion form a closed area when viewed from the top side.
 8. The liquidcrystal display of claim 7, wherein the depressed portion and theopening portion are arranged symmetrical to each other.
 9. The liquidcrystal display of claim 8, further comprising: a liquid crystal layersandwiched between the first substrate and the second substrate, theliquid crystal layer having liquid crystal molecules with a negativedielectric anisotropy; a first alignment layer and a second alignmentlayer formed on the common electrode and the pixel electrodes one byone, the first alignment layer and the second alignment layer aligninglong axes of the liquid crystal molecules to be perpendicular to thesubstrates; and a first polarizing plate and a second polarizing plateexternally attached to the first substrate and the second substrate. 10.The liquid crystal display of claim 9, wherein the first polarizingplate and the second polarizing plate have polarizing axes perpendicularto each other.
 11. The liquid crystal display of claim 10, wherein theliquid crystal molecules placed within the closed area defined by thedepressed portion and the opening portion have four average long axialdirections.
 12. The liquid crystal display of claim 11, wherein theaverage long axial directions make angles of 40-50° with respect to thepolarizing axes of the first polarizing plate and the second polarizingplate.
 13. The liquid crystal display of claim 3, wherein the depressedportion and the opening portion form a closed area when viewed from thetop side.